Drive unit for a luminescence display panel

• US 6,774,878 B2
• Filed: 09/11/2002
• Issued: 08/10/2004
• Est. Priority Date: 09/18/2001
• Status: Expired due to Fees

• Current Assignee: Tohoku Pioneer Company Limited (Pioneer Corporation)
• Original Assignee: Tohoku Pioneer Company Limited (Pioneer Corporation)
• Inventors: Yoshida, Takayoshi, Murakata, Masaki
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): Nguyen, Kimnhung
• Application Number:
  US10/238,850
• Publication Number:
  US 20030052842A1
• Time in Patent Office: 699 Days
• Field of Search: 345/45, 345/46, 345/76, 345/77, 315/169.1, 315/169.3, 315/169.4, 358/505
• US Class Current: 345/76
• CPC Class Codes: G09G 2310/04 Partial updating of the display screen
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 2310/062 Waveforms for resetting a plurality of scan lines at a time
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2330/04 Display protection
• CPC Class Codes: G09G 3/3216 using a passive matrix
• CPC Class Codes: G09G 3/3283 in which the data driver supplies a variable data current for setting the current through, or the voltage across, the light-emitting elements

Abstract

In a drive unit for a luminescence display panel employing organic EL elements as light-emitting elements and capable of reducing power consumed by the display panel when a partial scan mode is selected, when the partial scan mode is selected by a scan mode switching mean, a control is performed so that the ratio of a drive period (D3), during which the light emission of the light-emitting elements is controlled, to a reset period (R1) set by a reset control means is increased as compared with a case in which the ordinary scan mode is selected. Thus, the momentary luminance of the light-emitting elements can be lowered by further reducing drive currents or drive voltages supplied to the respective light-emitting elements. Accordingly, it is possible to further reduce the power consumption of the luminescence display panel as well as to prevent the deterioration of the light-emitting elements, which contributes to extend the life of the light-emitting elements.

Claims

1. A drive unit for a luminescence display panel comprising:

a plurality of drive lines and a plurality of scan lines intersecting each other;

a plurality of capacitive light-emitting elements connected between the scan lines and the drive lines at a plurality of intersecting positions by the drive lines and the scan lines;

scan mode switching means which capable of selecting a normal scan mode in which all effective light-emitting elements in the luminescence display panel are repeatedly scanned to control light emission and a partial scan mode in which part of the effective light-emitting elements in the luminescence display panel are repeatedly scanned to control light emission; and

one of reset control means for resetting all of the plurality of scan lines to the same electrical potential each time the respective scan lines are switched and reset control means for resetting all of the plurality of scan lines and at least drive lines that are driven next for light emission to the same electrical potential,

wherein when the partial scan mode is selected by the scan mode switching mean, a control is performed so that the ratio of a drive period, during which the light emission of the light-emitting elements is controlled, to a reset period set by the reset control means is increased as compared with a case in which the ordinary scan mode is selected.

2. A drive unit for a luminescence display panel according to claim 1, wherein when the partial scan mode is selected by the scan mode switching means, a reset period that is approximately the same as that when the ordinary scan mode is selected is set.

3. A drive unit for a luminescence display panel according to claim 1 or 2, wherein operation clocks having the same cycle are used to set the reset period and the drive period, and when the partial scan mode is selected by the scan mode switching means, a management is performed so that the number of counted-up operation clocks for setting the drive period is increased in accordance with the ratio of the drive period to the reset period as compared with the case in which the ordinary scan mode is selected.

4. A drive unit for a luminescence display panel according to claim 1 or 2, wherein operation clocks having a different cycle are used to set the reset period and the drive period, and when the partial scan mode is selected by the scan mode switching means, the operation clocks for setting the drive period has a cycle larger than that of the operation clocks used when the ordinary scan mode is selected.

5. A drive unit for a luminescence display panel according to claim 4, wherein the number of counted-up operation clocks for setting the drive period when the partial scan mode is selected by the scan mode switching means is made approximately the same as the number of counted-up operation clocks for setting the drive period when the ordinary scan mode is selected thereby.

6. A drive unit for a luminescence display panel according to claim 3, wherein the number of counted-up operation clocks for setting the reset period when the partial scan mode is selected by the scan mode switching means is made approximately the same as the number of counted-up operation clocks for setting the reset period when the ordinary scan mode is selected thereby.

7. A drive unit for a luminescence display panel according to claim 4, wherein the number of counted-up operation clocks for setting the reset period when the partial scan mode is selected by the scan mode switching means is made approximately the same as the number of counted-up operation clocks for setting the reset period when the ordinary scan mode is selected thereby.

8. A drive unit for a luminescence display panel according to claim 1 or 2, comprising luminance variable means for lowering the momentary luminance of the light-emitting element when the partial scan mode is selected by the scan mode switching means as compared with the momentary luminance when the ordinary scan mode is selected thereby.

9. A drive unit for a luminescence display panel according to claim 8, wherein the luminance variable means changes the drive currents applied to the respective drive lines.

10. A drive unit for a luminescence display panel according to claim 8, wherein the luminance variable means changes the drive voltages applied to the respective drive lines.

11. A drive unit for a luminescence display panel according to claim 1 or 2, wherein the light-emitting elements comprise organic electroluminescence elements.